Preparation Of Antibacterial Fiber Surface Using Quaternary Ammonium Salt Polymer By "Grafting Into” Method

Cotton fabric occupies a large market share in the textile industry due to its wearing comfort properties.However,it is very urgent to prepare antibacterial cotton products because cotton fabric is suitable for bacterial breeding and propagation.Among the antibacterial agents for cotton fabric,inorganic antibacterial agents are lack reactivity to form chemical bonds with cotton fibers,thus often leading to poor durability and potential biosafety risk.Natural antibacterial agents suffer from some shortcomings,such as limited resources,weak thermal stability and tedious processes.Organic synthetic antibacterial agents are poor heat resistance and the finishing processes of which are complex.In this study,quaternary ammonium salt(QAS)copolymer is used as an antibacterial agent to construct effective antibacterial coatings on the surface of cotton fabric and polyester/cotton blended(PTCO)fabric.Then,explore the durability of QAS copolymer composition on the modified cotton fabrics and PTCO fabrics.Evaluate the wearing comfort properties of cotton fabrics,such as water vapor permeability,moisture permeability and softness.Specific research contents are as follows:(1)In this work,[2-(methacryloyloxy)ethyl] trimethylammonium chloride(DMC),a quaternary ammonium monomer,was co-polymerized with methyl acrylate(MA)to prepare an antibacterial copolymer,Poly(DMC-co-MA).The obtained copolymer was grafted to the surface of cotton fibers by a "grafting into" method through the pad-dry-cure process to obtain durable antibacterial cotton fabrics.Further,to improve the grafting efficiency,the surface of cotton fiber was modified with carboxymethyl chitosan(CMC),building an amino-functionalized fiber surface via the esterification reactions and to increas the reactive site.Then,the MA unit ester group and CMC amino group in the QAS copolymer were aminated and anchored on the surface of cotton fiber to form cationic antibacterial coating.The results showed that the antibacterial cotton fabric could inactivate all Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus),showing high antibacterial ability.Even after 50 laundering cycles,more than 98.0% of the antibacterial rate could still be retained.The above chemical modification process did not cause the loss of water vapor permeability,water absorption and softness of cotton fabric.This study adopted a strategy to elaborate the "grafting into" method for preparing durable antibacterial cotton fabric by grafting QAS copolymers via pad-dry-cure process.The strategy is simple to operate,friendly to environment,easy to scale transformation and has important practical application value.(2)In this work,the Janus polyester/cotton(PTCO)fabric with antibacterial,hydrophobic and moisture permeability functions was prepared by a combination of pad-dry-cure and misting treatment processes.Firstly,through the pad-dry-cure process,1,6-hexanediamine(HDA)is covalently linked onto PTCO fabric surface via the ammonolysis reactions between HDA and polyester fiber,for building an amino-functionalized surface(PTCO-HDA).The single-sided surface of the obtained fabric is atomized with the above-mentioned QAS copolymer(Poly(DMC-co-MA))aqueous solution.The QAS copolymer is selectively grafted onto the cotton fiber surface to form antibacterial coatings via transesterification reactions.Then,Poly(lauryl methacrylate)(PLMA)is atomized to the other side of the PTCO fabric from a1,4-dioxane solution.By reacting with the amino functional group on the surface of the polyester fiber,the amide covalent bond was formed to realize the hydrophobic modification of the surface of the polyester fiber,and the polyester fabric of Janus was prepared.The results showed that the obtained PTCO fabric has 99.9% BR against E.coli and S.aureus,and formed hydrophobic properties on the unilateral surface(water contact angle up to 153°).The Janus PTCO fabric formed a hydrophobic gradient on both sides,which can accelerate the diffusion rate of water molecules from the hydrophobic side to the hydrophilic side when contact with water,improving the moisture permeability of the fabric and the temperature adjustment effect.The above finishing processes did not significantly damage the mechanical properties,water vapor permeability and softness of PTCO fabric,and brought comfort due to improved moisture permeability.The results of this study verify the combination of pad-dry-cure and misting treatment process to prepare Janus PTCO fabric,effectively.The method is simple and scalable,which is expected to broaden the application field of PTCO fabrics.